Book-like containers or albums have been widely utilized for packaging cassettes and other types of media materials. Such albums are basically of three-ply construction consisting of a stiff inside pair of trays of polyvinyl chloride (PVC), a flexible vinyl hinge strip interconnecting the trays, an outer cover of flexible vinyl, and rigid inserts of cardboard or chipboard between the cover and trays for rigidity.
It has been common practice to manufacture such vinyl albums by first laying the separate trays upside down in a nesting fixture, followed by positioning the hinge strips over the adjacent edges of the trays. Rigid inserts of cardboard or the like are then positioned over the trays and hinge strips, followed by a cover sheet. Any "trap-in" or clear vinyl overlay defining a pocket for a book jacket or the like, is then laid over the cover, after which the sealing die is actuated to seal the edges of the trays, hinge strips, cover, and any trap-in sheet by radio frequency (RF) radiation to secure the album. The completed albums are then removed from the fixture and inspected, and any excess material is stripped from the periphery of the albums before shipment to the customer for packing and resale as a packaged video product. Such albums have been available from Blackbourn, Inc., the assignee of the present invention, and others for years.
This construction technique results in albums of high quality but somewhat high unit cost. The relatively high unit cost has been due primarily to the extra time and labor involved in properly positioning and laying up the various pieces by hand in the nesting fixture. In addition, since overlying edge portions of the trays, hinge strip, and cover are sealed together to form spine rules, it has been necessary to slip an extra piece of insulating material between any trap-in and the hinge area of the cover to avoid sealing of the trap-in to the cover on the spine in order to provide a "full open" trap-in extending between the covers across the back of the album. This of course requires further time and labor, which can be significant factors in the manufacture of relatively low cost, high volume products of this type.
In 1980, Blackbourn produced and offered the "EconoPak" album in response to the need for a lower cost RF heat-sealed album of the same or similar quality. Instead of separate trays and a separate vinyl hinge strip between the trays, the Econo-Pak album incorporated a one-piece stiff molded sheet defining the trays and an integral spine liner portion therebetween, together with cardboard inserts between the trays and cover but not between the spine liner portion of the inner tray sheet and the spine portion of the outer cover sheet, and was otherwise constructed as before.
More recently, U.S. Pat. Nos. 4,407,410 and 4,432,827 have issued for a book-type cassette holder and method of making same. These patents show an RF heat-sealed album which is identical to the prior Blackbourn EconoPak, except for omission of the seals on the spine so that the integral spine liner portion between the trays and the spine portion on the cover can flex outwardly across their entire widths. Since this construction does not incorporate any seals or spine rules on the spine, it facilitates provision of a full open trap-in because there is no need to insulate the trap-in from any sealing along the spine. This construction has certain efficiencies over the albums with separate trays and vinyl hinging strips of the prior art. However, proper positioning and lay-up of the various components, which are done primarily manually, are still required and thus limit the efficiencies obtainable by this technique.
Even more recently, U.S. Pat. No. 4,555,290 has issued for a method of making such cassette holders on a mass production basis from stiff and flexible sheets of thermoplastics material unwound from reels. While this technique offers some advantages, there are still some disadvantages associated therewith. One significant disadvantage is that rigid inserts are still required for reinforcement, which of course increases material costs and can affect overall production speed even when the inserts are handled automatically. Since the albums are not sealed on the spine, they tend to require the additional rigidity provided by the inserts. This also means that proper tensioning of the flexible cover sheet is more critical, which can also affect overall speed of the system.
It will be appreciated that there is an increasing demand for prerecorded video cassettes and other products. There is thus a need for an improved video cassette album whose construction offers substantial manufacturing efficiencies over the prior art.